Essentially, since most of yall voted Run Changes and Playable Sans, I decided to combined the concepts.

During Snowdin, if you get the battle prompt, "But Nobody Came" before you reach Snowdin Town, then afterwards, the narrator, or Chara, will say something like:

"Don't you wonder what that bonehead is doing right now?"

Your perspective will change to Sans's perspective, with his soul changing from a normal monster soul, into one with a bright red outline.

This is meant to symbolized that we have control over his body for the moment.

Anyway, as Sans, you will choose dialogue choices, and overall actions which will change the story, similar to Run Changes.

Do you guys like this idea?